Tvheadend

Hi,

My TVHeadend muxes fail with tuning with a `Silicon Labs Si2168` chip. My setup is relatively simple (I think): ISP router - cable - WinTV-dualHD receiver (https://www.hdpvr2gamingedition.com/product.sc?productId=71&categoryId=1) - TVHeadend server

TVHeadend is run in a snap, version 4.2.8 (https://snapcraft.io/install/tvheadend/debian)

Following the discussion in https://tvheadend.org/boards/5/topics/46257 I run

./w_scan2 -f c -c HU

w_scan2-1.0.14 (compiled for DVB API 5.11)
https://github.com/stefantalpalaru/w_scan2

using settings for HUNGARY
Country identifier HU not defined. Using defaults.
scan type CABLE, channellist 4
output format vdr-2.0
output charset 'UTF-8', use -C <charset> to override
Info: using DVB adapter auto detection.
    /dev/dvb/adapter0/frontend0 -> CABLE "Silicon Labs Si2168": very good :-))

Using CABLE frontend (adapter /dev/dvb/adapter0/frontend0)
-_-_-_-_ Getting frontend capabilities-_-_-_-_
Using DVB API 5.11
frontend 'Silicon Labs Si2168' supports
INVERSION_AUTO
QAM_AUTO
FEC_AUTO
FREQ (48.00MHz ... 870.00MHz)
SRATE (1.000MSym/s ... 7.200MSym/s)
-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_
474000: sr6900 (time: 00:00.008) sr6875 (time: 00:01.516)
482000: sr6900 (time: 00:03.016) sr6875 (time: 00:04.520)
490000: sr6900 (time: 00:06.024) sr6875 (time: 00:07.524)
498000: sr6900 (time: 00:09.028) sr6875 (time: 00:10.532)
506000: sr6900 (time: 00:12.032) sr6875 (time: 00:13.536)
514000: sr6900 (time: 00:15.036) sr6875 (time: 00:16.536)
522000: sr6900 (time: 00:18.044) sr6875 (time: 00:19.544)
530000: sr6900 (time: 00:21.044) sr6875 (time: 00:22.552)
538000: sr6900 (time: 00:24.052) sr6875 (time: 00:25.556)
546000: sr6900 (time: 00:27.056) sr6875 (time: 00:28.560)
554000: sr6900 (time: 00:30.064) sr6875 (time: 00:31.564)
562000: sr6900 (time: 00:33.068) sr6875 (time: 00:34.572)
570000: sr6900 (time: 00:36.072) sr6875 (time: 00:37.577)
578000: sr6900 (time: 00:39.077) sr6875 (time: 00:40.581)
586000: sr6900 (time: 00:42.085) sr6875 (time: 00:43.585)
594000: sr6900 (time: 00:45.089) sr6875 (time: 00:46.589)
602000: sr6900 (time: 00:48.093) sr6875 (time: 00:49.593)
610000: sr6900 (time: 00:51.097) sr6875 (time: 00:52.601)
618000: sr6900 (time: 00:54.101) sr6875 (time: 00:55.605)
626000: sr6900 (time: 00:57.109) sr6875 (time: 00:58.609)
634000: sr6900 (time: 01:00.113) sr6875 (time: 01:01.617)
642000: sr6900 (time: 01:03.117) sr6875 (time: 01:04.621)
650000: sr6900 (time: 01:06.125) sr6875 (time: 01:07.625)
658000: sr6900 (time: 01:09.129) sr6875 (time: 01:10.629)
666000: sr6900 (time: 01:12.133) sr6875 (time: 01:13.637)
674000: sr6900 (time: 01:15.138) sr6875 (time: 01:16.642)
682000: sr6900 (time: 01:18.146) sr6875 (time: 01:19.646)
690000: sr6900 (time: 01:21.150) sr6875 (time: 01:22.654)
698000: sr6900 (time: 01:24.154) sr6875 (time: 01:25.658)
706000: sr6900 (time: 01:27.158) sr6875 (time: 01:28.662)
714000: sr6900 (time: 01:30.166) sr6875 (time: 01:31.666)
722000: sr6900 (time: 01:33.170) sr6875 (time: 01:34.674)
730000: sr6900 (time: 01:36.174) sr6875 (time: 01:37.678)
738000: sr6900 (time: 01:39.178) sr6875 (time: 01:40.682)
746000: sr6900 (time: 01:42.186) sr6875 (time: 01:43.686)
754000: sr6900 (time: 01:45.190) sr6875 (time: 01:46.694)
762000: sr6900 (time: 01:48.242) sr6875 (time: 01:49.746)
770000: sr6900 (time: 01:51.250) sr6875 (time: 01:52.755)
778000: sr6900 (time: 01:54.255) sr6875 (time: 01:55.759)
786000: sr6900 (time: 01:57.259) sr6875 (time: 01:58.763)
794000: sr6900 (time: 02:00.267) sr6875 (time: 02:01.767)
802000: sr6900 (time: 02:03.271) sr6875 (time: 02:04.775)
810000: sr6900 (time: 02:06.323) sr6875 (time: 02:07.827)
818000: sr6900 (time: 02:09.331) sr6875 (time: 02:10.835)
826000: sr6900 (time: 02:12.335) sr6875 (time: 02:13.839)
834000: sr6900 (time: 02:15.343) sr6875 (time: 02:16.843)
842000: sr6900 (time: 02:18.347) sr6875 (time: 02:19.847)
850000: sr6900 (time: 02:21.351) sr6875 (time: 02:22.855)
858000: sr6900 (time: 02:24.355) sr6875 (time: 02:25.859)

ERROR: Sorry - i couldn't get any working frequency/transponder
 Nothing to scan!!

I checked, and I have a valid TV subscription. How can I debug the scanning/tuning issue without a physical TV?